Base for tubes, lamps and the like



July 28, 1936; O BlGGs 2,049,152

BASE FOR TUBES, LAMPS AND THE LIKE Filed May 29, 1935 llllllillllllllhl INVENTOR BY Mi ATTORNEY Patented July 28, 1936 UNITED STATES PATENT OFFICE BASE FOR TUBES, LAMPS AND THE LIKE Application May 29, 1935, Serial No. 23,991

8 Claims.

This invention relates to tubes, lamps and similar devices and more particularly to improved base structures for such devices.

In certain types of devices e. g., radio tubes 5 or the like, it is desirable to provide a base consisting of insulating material, particularly where there are more than two contacts to the tube. For example it is a very general practice at present to provide the majority of types of radio tubes with bases of bakelite or similar insulating material, and to prevent relative movement between the tube envelope and the base, by using a cement bond therebetween. In order to provide a satisfactory bond of this type it is necessary to bake or cure the cement, but the extent of this baking operation is materially limited by the fact that the base material itself is a very poor heat conductor, and if the baking or cement curing is continued for any considerable length of time at the optimum temperature, there is danger of the base material becoming blistered or otherwise being deleteriously affected.

Accordingly one of ,the principal objects of the present invention is to provide a radio tube or similar device with a base which is attached to the tube envelope without the use of cement or similar bonding materials requiring baking or curing.

Another object is to provide novel means for locking a shell-type base to a tube or lamp envem lope.

A feature of the invention relates to an improved form of cementless based tube or the like employing a locking ring to prevent relative movement between the tube envelope and the base.

A further feature relates to a radio tube envelope having an improved form of molded seal or neck.

ganization, arrangement and relative location of parts which go to make up a relatively simple and cheap cementless based tube or the like.

Other features and advantages not specifically enumerated will be apparent after a consideration of the following descriptions and the appended claims.

While the invention will be described herein as applied to a radio tube of the so-called prongbase type, it will be understood that this is done merely for illustrative and explanatory purposes and not by way of limitation.

In the drawing Fig. 1 is a perspective view of part of a tube or lamp envelope having a molded neck according to the invention.

A still further feature relates to the novel or- I Fig. 2 is a view partly sectional, showing the manner of assembly of the base and envelope according to the invention.

Fig. 3 is a sectional view of Fig. 2 taken along the line 3-3 thereof.

Fig. 4 is a sectional view of the base of Fig. 2 taken along the line 33 thereof, but prior to the assembly of the envelope and locking ring.

Referring to Fig. 1, the numeral I indicates any well-known form of enclosing envelope such as is 10 ordinarily employed in radio tubes, lamps or the like, terminating at its lower end in a constricted or neck portion indicated generally by the numeral 2. Sealed to the neck portion 2 is any well-known type of reentrant stem terminating in 15 a press through which pass the various lead-in and support wires. The portion where the reentrant stem joins the neck of the envelope I, is customarily referred to as the seal and in accordance with the present invention this seal 20 area is formed, preferably by molding during the sealing operation, with an annular groove or channel 3, and at the same time the portion of the seal between the neck 2 and the rim 4 is flattened as indicated by the numerals 5 and 6 a and is also provided with shoulders I and 8. Thus during the sealing of the stem to the envelope neck, air under pressure may be admitted through the tubulation 9 to force the molten seal area outwardly against a mold of the desired shape. Preferably, also during this sealing and molding operation, the neck 2 is formed with a gentle taper I0 for purposes to be described, this taper being smooth and preferably frusto-conical.

The base II is preferably of the cylindrical shell type, and may be of bakelite or other similar insulating material. The bottom wall of the base has fastened therein in any suitable manner a plurality of contact pins or prongs l2, and while Fig. 2 shows only two of these prongs, it will be understood that there will be as many prongs as are required for the various lead-in wires for the device. The cylindrical wall of the shell base, is provided with two sets of recesses l3, l4 and l5, l6, adapted to receive corresponding locking projections l1, l8, l9, 20,-on a locking ring 2| preferably of spring metal or the like.

As shown clearly in Figs. 1 and3, ring 2| corresponds in width to the width of groove 3 in the molded seal so that the locking ring fits snugly in said groove, and the ring is shaped so that portions 22 and 23 closely fit against the corresponding portions 24 and 25 in the molded seal. Furthermore the locking ring is preferably 55 to register with the corresponding shoulders I and l to prevent relative turning between the bulb as a whole and the said ring; and also to prevent relative turning between the bulb and the base when the projections ii to 20 are in the recesses ii to it. Preferably the rim oi a base ii is provided with a taper II corresponding to the taper II on the bulb neck.

The manner of assembly 01' the bulb and base is substantially as follows: The locking ring II is slipped into the annular groove 3 in the position shown in Fig. 3. The ring is then compressed allowing the projections II, it, I. and 20 to clear the rim of the base ll, whereupon the bulb with the locking ring may be pressed downwardly until the projections on the locking ring expand into the recesses it to it. In this position the tapered portion I il 01' the bulb neck fits closely against the correspondingly tapered portion 30 of the base thus automatically centering the bulb with respect to the base. It will be understood of course that the width of the groove 3 is substantially the same as the width of the recesses II to It and the width '01 the locking ring, so that when the said ringexpands outwardly as described, the bulb is firmly held in engagement with the tapered rim 30. There is thus provided a mechanical locking engagement between the bulb as a whole and the shell base so that the said bulb cannot move relatively to the base either longitudinally or rotationally. This manner of attaching the base to the bulb eliminates the necessity oi employing cement which must be subjected to heat treatment to provide the necessary bond between the base and the bulb.

While one specific embodiment of the invention has been illustrated in the drawing, it will be understood that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What I claim is:

1. In combination a bulb having a groove at one end, a locking member in the form of a continuous ring-like spring lying in said groove, and a contact base of insulating material, said base having indentations on its inner wall to receive corresponding projections on said spring.

2. In combination a bulb having a groove at one end, an expansible continuous metal ring lying in said groove, a base of insulating material having its inner wall provided with a plurality of indentations, and a plurality oi projections on said ring adapted to enter said indentatiorm to 1 aosaiss provided with shoulders 20,21, 2: and is adapted prevent relative movement between said bulb and see.

3. In combination a radio tube having a cylindrical shell base of insulating material, said tube adapted to receive said base at one end and being 8 provided with a molded seal having a plurality of oppositely disposed shoulders and oppositely disposed fiat portions, a continuous locking ring surrounding the'saidend of said tube, said ring having shoulders registering with the first mentioned 10 shoulders, a plurality of indentations in the inner wall of said shell, said ring having expansible portions positioned within said indentations.

4. In combination a bulb having a neck provided with a tapered portion and a circumierenll tial groove, a shell base of insulating material having its rim tapered to correspond with the tapered portion or said neck, and an expansible ring interlocked with said base and with said neck said ring being seated in said groove;

5. In combination a bulb having a neck provided with a tapered portion and a circumierential groove, the bottom of said groove being provided with oppositely disposed shoulders,.a cylindrical shell base of insulating material having its 16 rim tapered to correspondto the taper on said neck, a locking ring mounted in said groove said ring having shoulders registering withthe shoulders in the bottom of said groove and having projections interlocking with said shell. W

6. In combination a bulb having a groove molded in the neck thereof, the base of said groove being formed with two flats and at least two diagonally disposed recesses, a shell base of insulating material adapted to fit over said neck, 35 said shell having at least two diagonally disposed recesses, and an expansible locking ring in said groove having portions seated in the first mentioned recesses and other portions seated in the second mentioned recesses.

7. The combination according to claim 8 in which the neck of the bulb and the rim of the shell are correspondingly-tapered at their point oi engagement.

8. A bulb having a neck portion and a reentrant stem sealed thereto, the area oi. the seal being molded to form a groove, the'base of said groove being provided with at least two diagonally disposed shoulders and two oppositely disposed fiat portions, 9. portion or the neck adjacent said groove being provided with a irustoconical taper.

ORRICK H. BIGGS. 

